Re: Type system for Perl 6

2010-02-05 Thread Jonathan Worthington
Giuseppe Castagna wrote: On 02/05/2010 11:29 PM, Jonathan Worthington wrote: And the odering in dispatch is not a type lattice as in Cecil but a topological ordering. Again I've no clue what that means. and all objects that do A are also B doers. So one could infer that we have A <: B. But note

Re: Type system for Perl 6

2010-02-05 Thread Giuseppe Castagna
On 02/05/2010 11:54 PM, Jonathan Worthington wrote: If you want to check if A inherits from B, do A.isa(B). If you want to check if A does B, do A.does(B). If you just care if A is somehow a subtype of B, but don't care why, do A ~~ B. Much of the time, the last of these is the important one.

Re: Type system for Perl 6

2010-02-05 Thread Jonathan Worthington
Giuseppe Castagna wrote: Yes I saw that inheritance is not subtyping. I would not share this decision since as an outsider, it seems to me that Perl6 has redundant syntax (too many different ways to express the same thing), so it is astonishing that in that case the choice was to use the same k

Re: Type system for Perl 6

2010-02-05 Thread Giuseppe Castagna
On 02/05/2010 11:29 PM, Jonathan Worthington wrote: And the odering in dispatch is not a type lattice as in Cecil but a topological ordering. Again I've no clue what that means. and all objects that do A are also B doers. So one could infer that we have A <: B. But note that this subtype relatio

Re: Type system for Perl 6

2010-02-05 Thread TSa (Thomas Sandlaß)
HaloO Mr Castagna, On Friday, 5. February 2010 23:13:25 you wrote: > Actually I noticed an old post you did on this list 5 years ago. It > contained the following drawing Yeah it's a long time. And I've sort of lost interest in type theory. But then I tried to persuade the list of a sophisticated

Re: Type system for Perl 6

2010-02-05 Thread Jonathan Worthington
Hi, TSa (Thomas Sandlaß) wrote: There is no formally defined subtype relation or rules for subsumption. A type is called narrower without details what that means. A is a subtype of B if A ~~ B, where ~~ is the smart-match operator..It's up to the type object on the RHS how it responds to this.

Re: Type system for Perl 6

2010-02-05 Thread Giuseppe Castagna
On 02/05/2010 10:53 PM, TSa (Thomas Sandlaß) wrote: HaloO Mr Castagna I'm delighted to have you interested in Perl 6. I know your book and articles and have argued for a type system of Perl 6 here on the list for quite a while. Wow, so actually somebody read it! :-) Thank you Unfortunately I

Re: Type system for Perl 6

2010-02-05 Thread TSa (Thomas Sandlaß)
HaloO Mr Castagna On Friday, 5. February 2010 16:43:26 you wrote: > I see I'm going out of the scope of this list. I apologize for spamming, > but please continue to post here or send me by PM every information about > Perls 6 types. I'm delighted to have you interested in Perl 6. I know your boo

r29645 - docs/Perl6/Spec

2010-02-05 Thread pugs-commits
Author: lwall Date: 2010-02-05 19:39:57 +0100 (Fri, 05 Feb 2010) New Revision: 29645 Modified: docs/Perl6/Spec/S03-operators.pod Log: [S03] be more specific about bitwise semantics Modified: docs/Perl6/Spec/S03-operators.pod ===

Re: Type system for Perl 6

2010-02-05 Thread Giuseppe Castagna
Thank you very much for your answers. As I said in my post I knew the synopsis, but I hoped to have something more precise. I will explore it again by using Timoty roadmap On 02/05/2010 01:59 AM, Darren Duncan wrote: G. Castagna: Covariance and contravariance: conflict without a cause. ACM T